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This article describes the improvements and issues that are fixed in the Azure File Sync Agent v15.1 release that is dated September 2022. Additionally, this article contains installation instructions for this release.

Improvements and issues that are fixed

Low disk space mode to prevent running out of disk space when using cloud tiering

Low disk space mode is designed to handle volumes with low free space more effectively. On a server endpoint with cloud tiering enabled, if the free space on the volume reaches below a threshold, Azure File Sync considers the volume to be in Low disk spacemode.  

In this mode, Azure File Sync does two things to free up space on the volume: 

  • Files are tiered to the Azure file share more proactively.

  • Tiered files accessed by the user will not be persisted to the disk.

To learn more, see the low disk space mode section in the Cloud tiering overview documentation.

Fixed a cloud tiering issue that caused high CPU usage after v15.0 agent is installed

Miscellaneous reliability and telemetry improvements

More information about the Azure File Sync Agent v15.1 release

  • This release is available for Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, and Windows Server 2022 installations.

  • The agent version for this release is

How to obtain and install the Azure File Sync Agent 

The Azure File Sync agent v15.1 release is no longer available due to a cloud tiering bug.

If v15.1 is installed on your server and cloud tiering is enabled, you may notice one of the following issues:

  • Memory usage is higher after upgrading to v15.1

  • Storage Sync Agent (FileSyncSvc) service intermittently crashes

  • Files are failing to recall with error ERROR_INVALID_HANDLE (0x00000006)

If you’re experiencing one of these issues on a server with v15.1 installed, please open a support case and our support team will walk you through the steps to resolve the issue.

This issue has been fixed in the Azure File Sync agent v15.2 release: Azure File Sync Agent v15.2 Release – November 2022.

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